The invention comprises an optical fibre-amplifier and a transmission system with optical fibre-amplifier in accordance with the nature of the independent claims.
From the literature, a multiplicity of optical fibre-amplifiers is known. Optical fibre-amplifiers consist of a special fibre, the core of which is doped with a rare-earth element. By pumping the rare-earth ions with a suitable pump wavelength, an inversion condition, which can be called by an incoming optical signal is generated in the fibre. The amplification profile of such a fibre-amplifier exhibits a maximum, where the maximum depends on the type, the quantity of the rare-earth element and a co-doping. The aim in using optical transmission systems is to get as wide and flat an amplification curve as possible. Specifically in wavelength division multiplex (WDM) a flat and adequately wide amplification profile of the fibre-amplifier is desired. The temperature behavior of a fibre amplifier, however, causes problems. The problem is, that the spectral transmission of the passive components of a fibre amplifier and the spectral behavior, specifically the amplification profile of the active fibre, change with temperature. This variable temperature behavior has an unfavorable effect on the amplification profile, particularly on the desired flat amplification curve of the fibre-amplifier.
From U.S. Pat. No. 5,177,562 a method is known for influencing the temperature behavior, which has an unfavorable effect on the amplification profile of the fibre amplifier. It is proposed to optimize the pump performance of the pump laser as well as the pump wavelengths to exert an influence on the amplification profile in a suitable manner, in order to compensate for the temperature effects. The proposed method effects a temperature compensation for the behavior of the amplifying fibre, but does not take the temperature-behavior of other components in an optical fibre-amplifier into account.